Effects of prolonged exposure time in traumatic environment on behavior differences and HPT axis in male and female rats / 中华行为医学与脑科学杂志

ABSTRACT

Objective:To investigate the effects of prolonged exposure time on the behavior and hypothalamus-pituitary-thyriod(HPT) axis in post-traumatic stress rats.Methods:Fifty female rats and fifty male rats were respectively divided into 5 groups according to the random number table( n=10 in each group) blank group, D1F group(exposed in trauma environment for 2 min, sampled immediately after exposure), D1Y group(exposed in trauma environment for 90 min, sampled immediately after exposure), D4F group(exposed in trauma environment for 2 min, sampled after trauma environment fear memory test on the fourth day), D4Y group(exposed in trauma environment for 90 min, sampling after fear memory test of trauma environment on the fourth day). The anxiety and fear behaviors of rats were measured by capture rejection test, and the serum levels of thyrotropin-releasing hormone(TRH), thyrotropin(TSH), free triiodothyronine(FT 3), and free tetraiodothyronine(FT 4) were measured by enzyme-linked immunosorbent assay(Elisa). Results:(1)The rejection degree of male D4Y group and male D4F group were lower than that of blank group((1.70±1.77)points, (0.80±1.23)points, (3.60±1.43)points, P<0.05). There was no difference between female D4F group and blank group( P>0.05), and the rejection degree of female D4F group was lower than that of blank group((0.90±1.29)points, (3.30±1.57)points, P<0.05). (2)The levels of FT 3 and FT 4 in male D4F group were higher than those in blank group( P<0.05). Compared with male D4F group, the levels of FT 3 in male D1F group, D1Y group and D4F group were lower( P< 0.05). Compared with male D4F group, the levels of FT 4 in male D1F and D1Y group were lower((12.19±0.97)pmol/L, (11.19±0.21)pmol/L, (11.24±0.73)pmol/L, P<0.05). Compared with female blank group, female D1F group and female D4Y group, TRH level of female D1Y group decreased( P<0.05). Conclusion:Prolonging the exposure time in the trauma environment can reduce the stress activity of HPT axis in male rats, and the anxiety and fear behavior tend to be more obvious, while for female rats, although the anxiety and fear behavior tend to be normal, the HPT axis should not be activated after trauma.